It is known to connect MEMS switches to form a switching array, such as series connected modules of parallel switches, and parallel connected modules of series switches. An array of switches may be needed because a single MEMS switch may not be capable of either conducting enough current, and/or holding off enough voltage, as may be required in a given switching application.
An important property of such switching arrays is the way in which each of the switches contributes to the overall voltage and current rating of the array. Ideally, the current rating of the array should be equal to the current rating of a single switch times the number of parallel branches of switches, for any number of parallel branches. Such an array would be said to be current scaleable. Current scaling has been achieved in practical switching arrays, such as through on-chip geometry and interconnect patterning. Voltage scaling has been more challenging to achieve, as this may involve passive elements in addition to the switching structure.
In concept, the voltage rating of the array should be equal to the voltage rating of a single switch times the number of switches in series. However, achieving voltage scaling in practical switching arrays has presented difficulties. For instance, serially-stacked switches involving B2B switching structures may present unique challenges such as due to the need to isolate (e.g., from cross talk) the voltage that controls the switching operation and the voltage being switched. More specifically, a B2B switching structure generally involves a voltage reference location (e.g., midpoint of the B2B structure) that should reference the beam voltage to the voltage controlling beam actuation (the gating voltage). For example, the midpoint of the B2B structure, if not appropriately electrically referenced, could electrically float, and in a series-stacking of such switches, this could lead to the formation of a relative large differential voltage across a free end of a movable beam of the switch and a stationary contact, (e.g., exceeding the “with-stand” voltage ratings of a given switch) which could damage the switch when the switch is actuated to a closed condition.